Equalizer performance enhancements for broadband wireless applications

Abstract

A system and method for enhancing the performance of an equalizer in a modem. Multiple techniques are disclosed which improve the modem performance. A first technique uses stored parameters for each burst from each remote site to demodulate a received data stream. A second technique compensates for the gain droop caused by storing parameters across each burst. A third technique minimizes errors caused by adapting the equalizer coefficients for each data burst by analyzing the SN ratio and error rate of the received burst. A fourth technique improves the convergence of the equalizer by using a two-part preamble, whereby both parts are transmitted using different modulation techniques. A fifth technique is provided which performs a soft reset of the modem without performing a complete reset of the modem. A sixth technique determines a modem adaptation factor based on the expected modulation type of an incoming burst transmission. A seventh technique calculates a phase correction value for the stored tap values and applies the value to the incoming signal.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates to a home base modem system in a wireless communication system that provides telephone, data and Internet connectivity to a plurality of users.[0003]2. Description of Related Art[0004]Several systems are currently in place for connecting computer users to one another and to the Internet. For example, many companies such as Cisco Systems, provide data routers that route data from personal computers and computer networks to the Internet along conventional twisted pair wires and fiber optic lines. These same systems are also used to connect separate offices together in a wide area data network.[0005]However, these systems suffer significant disadvantages because of the time and expense required to lay high capacity communications cables between each office. This process is time consuming and expensive. What is needed in the art is a high capacity system that provides data links between offices, but d...

AI Technical Summary

Benefits of technology

[0010]In one embodiment, the method comprises minimizing errors caused by adapting equalizer coefficients for each data burst from a remote site to a home base comprising retrieving a first equalizer coefficient for a current remote site, demodulating a data burst from the current remote site, determining the S / N ratio for the received burst, determining the error rate from the demodulated burst, comparing the determined S / N ratio and error rate to defined thresholds, and updating the first equalizer coefficient based on the comparisons.

[0011]In one embodiment, the method comprises improving the convergence of an equalizer in a multi-modulation modem using a two part preamble comprising defining a first part of a preamble with a lower order section, wherein the lower order section is transmitted using QPSK modulation, defining a second part of the preamble with a higher order section, wherein the higher order section is transmitted using QAM 64 modulation, transmitting both the first and second parts of the preamble, receiving the transmitted preamble, and converging the equalizer based on the received preamble.

Problems solved by technology

However, these systems suffer significant disadvantages because of the time and expense required to lay high capacity communications cables between each office.

This process is time consuming and expensive.

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